code: def SInt64ByteSize(field_number, int64):
      return UInt64ByteSize(field_number, ZigZagEncode(int64))
  
imports: import struct
  from google.protobuf import descriptor
  from google.protobuf import message
label_desc: Use image node_id 11 for calling a global function with example usage: SInt64ByteSize(field_number, int64) and returns: UInt64ByteSize